Air propeller driving system



June 19, 1945.

R, PR'AUSE ET AL, .2,378,580

\ AIR PROPELLER DRIVING SYSTEM Filed oct. 2.2, 1940 4 Sheets-sheet 1 m4 /aa f r---L f l r-I i3 o June 19, 1945. RQ PRAUSE E1- A| 2,378,580

AIR PROPELLER DRIVING SYSTEM v Filed Oct. 22,- 1940 4 Sheets-Sheet -2 FROM PROPELLE/' Juhe 19, 1945. v R. PRAUs ETAI.

AIR PROPELLER DRIVING SYSTEM Filed Oct. 22, 1940 4 Sheets-Sheet 3 ""'I Fab er?? Pza/ase Junevla, 1945-. R, PRA'USE TAL 2,378,580

AIR PROPELLER DRIVING SYSTEM Filed oct. 22. 1940 4 sheets-,sheet 4 Patented June 19, y1945 Robert Piause and Lukas Schmid, Augsburg,

Germany;- vested'in the Alien Property Custovdian' Application octobery 22,1940, serial No. 362,280 In Germany June 10, 1938 i claims.' (c1. k17o-163) The present invention relates toimprovements in variable pitch propellers for aircraft, and more particularlyvto propellers which vare controlled by an automatic speed regulator duringr normal lflight and which are further controlledy by a manual. control lever to obtain' feathering or braking'positions. l f- VHeretofore, adjusting systems for variable pitch vpropellers yir'icluded only one source of mechanical power such as a hydraulic cylinder, an electric motor, or the propellerdriving motor itself. As it is necessary to vobtain sensitive' pitch control during normal flight, such' a singlevv source of mechanical power must be adapted to` operate at a low adjusting speed. This involves considerable delayV particularly when changing the pitch from a coarse pitch'to braking position or from braking position to climbing position.

Itis vtherefore an important object;,of the present invention to provide an adjustingsystem for variable pitch propellers which, 'although sensitive in cooperation with the yautomatic speed regulator, permits of a rapid adjustment to feathering or braking positions or to normal vnight positions.

Anothery object of ,the present invention is to providev a strong and reliable adjusting system for Variable pitch propellers. v Withithese and -other objects in View,l as may become apparent fromthe following, the invention consists not only in the structures herein described and illustrated in the drawings,r but includes further structures coming within the scope of the claims. n

The character of the inventionwillbe underin ,which- Fig. '1 is a schemati'cal view ofapropeller adjusting device embodying.theinventionx. c

Fig. 2.is a. diagrammatic view of .thecomplete yplantiricluding the vcontrol members. d i

Fig. 3 is a plan view, partly in a substantially horizontal cross section, .of an adjusting device in Which the sleeve setting lever is connected by a CardanV arrangement with the members linked to ing sourcesof mechanical power for the adjustment of the propeller blades. Each of these sources of mechanical power is adapted to act in rsource takes place at a low speed at this range of .pitch is comparatively small and requires sensitiveness more than speed inthe adjustment.

. Lowadjustment speed involves smallerforces for mechanical power is intended for operation onlyr stoodby referencev tothe accompanying drawings controlling this source of mechanical powerrand with a given adjustingforce of the automatic speed regulator,a greater sensitiveness. The

force requiredffor controlling this source of mechanical power,k including frictional.losses, may be reduced below 1% and even to values inthe order of 0.15% of the adjusting force of the automatic speed regulator.` 'Ihe smaller this value, known asy deg-ree ofinsensibility, thesmaller'a deviation from the normal speed will be suicient to cause the adjusting system to operate and, by changingv the pitch of the propeller blades, Ato restore the-normal speed. The second source of when extreme 4positions of the propellerblades, Such as feathering or braking positions, are desired and for manual control. The high adjustving speed required for this operating range may be attainedby suitable means and sensitiveness is unimportant during the high speed adjustment. The adjusting speed of the second source of mechanical power should ordinarily be a multiple of the adjusting speed of the rst source of mechanical power controlled by the automaticspeed regulator. f

Both of the drives lmay include electric motors, one of which is tted with a'reduction gear of higher ratio, or the slow drive may include Vhydraulic means.

Preferably the two sources of mechanical power are arrangedto act upon the opposite ends of a two-armed lever which surrounds a slidabler adjusting sleeve and actuates the same, for'turnadjustment of propeller blades by a sleeve slidable onthe propeller shaft is known per se andis herein employed in combination with two independent sources of mechanical power.

, By reason of this particular double driving system, and more particularlyby the rapiddrive, the adjusting` mechanismk is exposed to high stress. Wear, one or more elements permitting a Cardan- Therefore, in order to avoid premature` motion are provided between the stationary points of the device, such as the engine casing, or gear casing, and the sleeve sliding on the propeller shaft, thus avoiding jamming action in the mechanism. It has been foundthat with a suspension of the adjusting device permitting swinging of the two-armed adjusting lever in one plane only, considerable damages may occur on the slidable sleeve, even after a few hours of flight, while these disadvantages can be avoided by the Cardan suspension or gimbal mounting.

As here shown, the gimbal mounting may be effected by connecting both ends of the twoarmed adjusting lever by self-aligning ball bearings or by Cardan joints with the driving means engaging it at its opposite ends. By way of alternative, a Cardan joint or gimbal mounting may be provided between the two-armed lever and the sleeve.

According to a further feature of the invention the slidable sleeve may consist of artificial resins on the phenol-aldehyde basis, such as Bakelite Referring now to the drawings in greater detail, and first to Fig. 1, it will be noted that the propeller blades I and 2 are mounted to be turnable in ball bearings ||JI seated in the hub 3 of the propeller. Interiorly threaded setting levers 4| are xedly screwed on the bases of the propeller blades and connected through connecting rods 42 to a sleeve 43 constituting the inner ring of a ball bearing whose outer ring 44 is connected to a surrounding two-armed adjusting or setting lever 46, by means of trunnions 45. The upper arm of said setting lever 46 is engaged by the piston rod 41 of a cylinder 48 which is mounted on the motor or gear casing |02 of the airplane and operated by oil under pressure. Also mounted on this casing is an electric motor 50 which by means of any suitable transmission gear operates on the lower arm of the lever 46. In the embodiment illustrated in Fig. 1, the motor shaft 5| itself is constructed as a threaded spindle engaged by a nut member 52 which is operatively connected to the lever 46, whereby the adjusting force is transmitted in a very simple manner.

The supply of oil to the pipes |03 and |04 of the cylinder 48 is under the 4control of an automatic speed regulating device (not shown) while with the speed regulating device cut o ff the connecting point of the piston rod 41 with the lever 46 forms a stationary pivot for swing motion of the lever 46 under action of the moto-r 50.

On the other hand, as the hydraulic mechanism 41, 43 is operating, the electromotive drive 50, 5I,

52 is motionless and the link between the lever 46 l and the end of the nut 52 acts as a pivo-t for the lever 46, since the nut 52 is self-locking on the spindle 5I.V It follows that on operation of the piston in the cylinder 48 the lever 46 is swung about this lower pivot, taking along the sleeve 44.

During control of the propeller blades by the electric motor 50 the same is switched off as the position of the propeller blades desired at the time has been reached. This is achieved by cooperation of the spindle nut 52 with contacts 53 in such a manner that the spindle nut 52 on engagement with one of said contacts closes or opens an electric circuit (not shown). A separate selection switch (not shown) serves to determine the operative contact 53.

Fig. 2 illustrates the general arrangement of the control means for the operation of the adjustable propeller. In this case, electric motors have been provided for both the automatically controlled, slowly acting drive and a manually operated quickly acting drive. The blades I and 2 of the adjustable propeller are turned by swinging the lever` 46, as in Fig. 1. The upper end of this lever is acted upon by an electric motor 60, through a speed reducing gear 6|, making up the slow drive. A centrifugal regulator 58 controls the speed of the motor 60, through a relay 59. To this end, the centrifugal regulator 50 is adjusted to maintain a predetermined propeller speed, which advantageously depends on the position of the gas control lever. As the actual propeller speed falls below this speed or exceeds the same, the centrifugal regulator will readjust the propeller blades accordingly. For instance, if the propeller speed becomes less than the predetermined speed, the regulator 58 through the relay `59 will operate the motor 60 in such a direction that the pitch of the propeller blades is decreased, whereby the driving motor is relieved and the speed may go up again. On the other hand, if the actual propeller speed exceeds the predetermined speed, the regulator will cause an oppositely directed blade adjustment, or an increase of the propeller pitch and increased load for the driving engine of the airplane, whereby the speed is slowed down.

A switch l62 permits selective operation of the automatic or manual adjusting system by engagement of its lever 63 with the contact 64, switching in the automatic system, or the contact 65, switching off the automatic system and switching in the manual adjusting device.

If the manual system has been selected by engagement of lever 63 with contact 65, the system may be operated by a push button switch 66, which in most instances will be combined with, or mounted on, the accelerator and actuates a quick adjustment motor 68,*through a relay 61, whereby the propeller blades may be turned into a position for gliding.

The gas lever or accelerator which is indicated at 10, may be set to various positions. V is the open throttle position for normal operation; L is the idle running or no load position. If the lever is swung from the position V beyond position L, the propeller by means of a controller cylinder or drum type switch connected to the lever 10 is automatically set to a braking position which is independent from the position of the lever 63l of switch 62. Suitable means in the form of a link, brake or the like are provided to mark the no load position for the pilot.

The source of current for the propeller adjusting plant is indicated at 69 in the form of a storage battery.

Referring to Fig. 4, the propeller blades are mounted to turn in the propeller hub 3, as in the above mentioned constructions, the hub 3 being coupled with a hollow propeller shaft 4 by toothed end faces 5. An interior threaded member 6 serves for connecting the two parts. On the rear side, the shaft 4 may be constructed corresponding to the shape of the coupling on the motor shaft and it" may be connected to the motor shaft by means of bolts 1. A bushing 8 consisting of plastic material and morev particularly of an artificial resin material of the phenol-aldehyde type including textile admixtures is mounted on the shaft 4 by means of screws 9. Slidably seated on the bushing 8 is a sleeve I0 having lugs or eyelets I I, Fig. 3, to which connecting rods I2 are jointed which on their opposite ends are jointed to the adjusting levers I3 of the propeller blades. Said levers I3 by means of their female threads are frxedly screwed to the ba'se of their propeller blades, so that the propeller blades and 2 can -matic speed governor.

fbe turned byswingingthe levers I3. The ringshaped-setting lever or traversell'engages around the sleeve vIII and is j ointed'Cardan-fashion, at two oppositey pointsA I and II, to members I 'and 2l, Fig. 3, establishing the. connection with the respective driving mechanisms, 54 and 51.

Thefring -I4 has trunnions 30 and' 3I, Fig. 5, on which is pivoted'an interior holder ringy 32 for a `ball bearing. 33, (Fig. 3) whosel inner race ring 34is seated on the sleeve I 0,' being forcedagainst the. st'op face' or jcollar 36 of the sleeve I0 by means of a threaded ring (Fig 4).' 'A further threaded ring 31 which is screwed intov the lholder ring 32 serves for securing 'the outer racering of the ball bearing in the holder ring;A The slidable sleeve' Iis secured againstA turning on the bushing 8 bymeans 'of a key'38 engaging into a slot 39 of the bushing 8 the length of which corresponds' to the maximum stroke of the slide'motion.

The upper end ofthe two-armed lever or-*ring I4 is linked to the piston rod of the cylinder54 by means of a connecting rod I5, and a trunnion larwhich is supported in self-aligning ballr bearing I8 ofthe lug 20 on the ring I4. I t follows that the traverse ring I 4 owing to the provision of the Y lball bearing I9 is swingablewith respect to the rconnecting rod I5 around two axes at right angles to each other.

Referring now tothe opposite side of lthe `traverse: ring I4, theelectrici motor 51 (Fig. `3) through a reduction gear 56 drives a; threaded spindle 2l which is supportedinl a self-aligning ball bearing indicated at 22, so as to be swingable ping ring 2,9 is'provided on the freeend ofthe spindle 2I. displaced by 90 with respect tothe trunnions 30 and 3|, Fig. 5. v

The piston in the cylinder 54', Fig. 3, is moved by feeding or discharging oil under pressure through the pipes 55, under control of an `auto- During operation of the piston in the ,cylinder 54 the motor 51is switched off. The spindle 2l therefore stands stil1 and its nut 23 is stationary with respect to theaircraft. The traverse ring I4 therefore may swing about the pivot 1I and take along the slidable sleeve I 0.

As the plant is switched over to control bythe motor 51, the traverse ring "I4 becomes swingable about the pivot formed by the vpin I8, which is supported in the ball bearing I9 and held in position 'by the connecting rod I5, which is locked by the liquid in the cylinder 54. The result of this swing motion of the traverse is the same as that lof a swing motion caused by operation of the hydraulic drive, except that the adjustment is effected ata considerably higher speed.` If a kind of wabbling motion of the traverse I4 or ofthe slidable sleeve I0 is caused owing to the forces acting during the flight, the traverse member The suspension points I and lI-arel orthesleeveowing to the provision of the ball bearings I9 and 24 may freely yield to s uch forces so that jamming andconsequent avoided.

Any possible edgewise pressing which might vstill occur isv held within admissible limits by provision of the bushing 8 of artificial resin.

high wear are A modified arrangement for permitting Cardanmotion ofthe parts is illustrated iny Fig.l 6. In this arrangement,` the traverse' ring I4 is connected' Cardan-fashion with the slidable sleeve I0 or with the holderA ring 32 of the ball bearingi33 on this sleeve by means of a further ring 32 which is swingable about the trunnions 30 and 3I, while the holder ring 32 in turn is swing'able perpendicularly thereto about the'trunnions 30 and 3|' ofthe ring 32'.

The present inventionhas been described in detail' with reference to'specilic embodiments. It is to be understood, however, that the invention is not limited by such-specific reference but'is broader in scope and capable of other embodiments than those specifically described and illustrated in the drawings.

We claim: f

1. In an adjusting system for the propeller blades' of a variable pitch propeller provided with n an automatic speed regulator and va manual control lever the combination of'y a propeller shaft, a sleeveslidably mounted on said propeller shaft,

meansoperatively connecting's'aid sleeve with said propeller blades andv adapted to transform `sliding motion of said sleeve into turning motion of said propeller blades, a twofarmed lever'operatively engaging said sleeve, a first source of power adapted to act upon' one end of said leveriin either direction of adjustment at low adjusting speed', said first source of power'being'subject to control by. said automatic speed regulator,l a second source ofk power adapted to act upon another end of said lever in either direction of adjustment separately from said first source of power and at an adjusting speed whichis a multiple of the adjusting speed produced by said rst source of power, and said second source of power being subject to control by said manual control lever.

2. In an adjusting system for the propeller blades of a .variable pitch propeller provided with an automatic speed regulator anda ymanual controllever the combinationof, a propeller shaft, a

sleeve slidably mounted on said Apropeller shaft, means operatively. connecting said lsleeve with said -propeller blades -andadapted to transform sliding trol lever the combination of, a propeller shaft, a

sleeve slidably mounted on said propeller shaft, means operatively connecting said sleeve with said propeller blades and adapted to transform sliding motion of said sleeve into turning movement of said propeller'blades, a two-armed lever operatively engaging vsaid sleeve, first driving means for said leverengaging one end thereof including a hydraulic actuated piston subject to control of said automatic speed regulator, and second driving means for said lever engaging another end thereof including an electric motor subject to control of said manual control lever.

4. In an adjusting system for the propeller y blades of a variable pitch propeller provided with` an automatic speed regulator and a manual control leverthe combination of, a propeller shaft,

va sleeve slidably mounted on said propeller shaft,

means operatively connecting said sleeve with said propeller blades and adapted to transform sliding motion of said sleeve into turning movementl of said propeller blades, a two-armed lever operatively engaging said sleeve, Cardan joints at both ends of said lever, a first source of mechanical power adapted to act upon one of said Cardan joints in either -direction of adjustment at low adjusting speed, said first source of mechanical power being subject to control by said automa-tic speed regulatora second source of mechanical power adapted to act upon the other ofv said Cardan joints in either direction of adjustment separately from said first source of mechanical power and at an adjusting speed which is a multiple of the adjusting speed produced by said first source of mechanical power, and said second source of mechanical power being subject to control by said manual control lever.

5. In an adjusting system for the propeller blades of a variable pitch propeller provided with `an automatic speed regulator and a manual control lever the combination of, a propeller shaft, a sleeve slidably vmounted on said propeller shaft, means operatively connecting saidl sleeve with said propeller blades and adapted to transform sliding m-otion of said sleeve into turning movement of said propeller blades, a two-armed lever operatively engaging said sleeve, a gimbal mounting between said sleeve and said lever, a first source of mechanical power adapted to act upon one end of said lever in either direction of adjustment at low adjusting speed, said first source of mechanical power being subject to control by said automatic speed regulator, a second source of mechanical power adapted to act upon another end of said lever in either direction of adjustment separately from said rst source of` mechanical power and at an adjusting speed which is a multiple of the adjusting speed produced by said first sourceof mechanical power, and said second source of mechanical power being subject to control by said manual control lever.

6. In an adjusting system for the propeller blades of a Variable pitch propeller provided with an automatic speed regulator and a manual control lever the combination of, a propeller shaft,

a bushing of non-metallic material mounted on said propeller shaft, a sleeve adapted to slide upon said bushing, means operatively connecting said sleeve with said propeller blades and adapted to transform sliding motion of said sleeve into turning movement of said propeller blades, a twoarmed leveroperatively engaging said sleeve, a rst source of mechanical power adapted to act upon one end of said lever in either direction of adjustment at low adjusting speed, said first source i of mechanical power being subject to control by said automatic speed regulator, a second source of mechanical power adapted to act upon another end of said lever in either direction of adjustment separately from. said first source of mechanical power and at an adjusting speed which is a multiple of the adjusting speed produced by said iirst source of mechanical power, and said second source of mechanical power being subject to control by said manual control lever.

7. In an adjusting system for the propeller blades of a variable pitch propeller provided with an automatic speed regulator and a manual control lever the combination of, a propeller shaft, a sleeve slidably mounted around said propeller shaft, a bushing of non-metallic material of the phenol-aldehyde resin type mounted within said sleeve, means operatively rconnecting said sleeve with said propeller blades and adapted to transform sliding motion of said sleeve into turning movement off said propeller blades, a two-armed lever operatively engaging said sleeve, a first source of mechanical power adapted to act upon one end `of said lever in either direction of adjustment at low adjusting speed, said rst source of mechanical power being subject to control by said automatic speed regulator, a second source -of mechanical power adapted to act upon another end of said lever in either direction of adjustment separately from said rst source of mechanical power and at an adjusting speed which is a multiple of the adjusting speed produced by said iirst source of mechanical power, and said second source of mechanical power being subject to control by said manual control lever.

ROBERT PRAUSE. LUKAS SCHMID. 

